Sure, here are some travel tips for Florianópolis, Porto Alegre, and Gramado:

Best Time to Visit:
For beach going in Florianópolis, December to March is ideal but this is also peak season. For general sight-seeing, and a visit to Porto Alegre and Gramado, May through September offer a comfortable climate and less crowds.

Route and Accessibility:
You can start your journey in Porto Alegre, as it has an international airport. From there, you can take a bus or drive to Gramado, which takes about 2 hours. After spending some time in beautiful Gramado, you can go back to Porto Alegre and catch a flight to Florianópolis, which is a short flight away.

Altitude and Acclimatization:
All of these places are near sea level, so altitude sickness isn't a concern.

Accommodation and Booking:
Submit your booking well in advance for accommodations, especially if you're travelling during peak season. There's a range of options from upscale hotels to more budget-conscious pousadas (guesthouses).

Clothing and Essentials:
For Florianópolis, bring beachwear and sunscreen. For Gramado, depending on the season, slightly warmer clothing might be necessary, especially if visiting during the winter months (June through September). Don't forget comfortable shoes for sightseeing.

Health and Safety:
Remember your travel insurance. Also, while cities in Brazil are generally safe, it's always good practice to watch over your belongings.

Local Etiquette and Respect:
Brazilians are warm and friendly. Respect the local customs and cultures. Learning a few phrases in Portuguese can also enrich your interaction with the locals.